The application relates more particularly to a seal intended to be mounted in an aperture or a similar opening in a casing or an analogous envelope in order to provide sealing between this casing and a moving machine or motor element, such as a rotary axle or shaft, passing through said aperture.
This type of seal generally has a circular structure at its external and internal peripheries, and incorporates a metallic support ring.
The art discloses seals which have a sealing washer equipped with a dynamic sealing lip consisting of a polytetrafluoroethylene (PTFE) composition. Usually, these seals comprise a static seal consisting of an elastomer material. A support body is coated there by injection-moulding of an elastomer material, the material being shaped so as to obtain a region of attachment for the dynamic sealing lip and a static seal.
Also disclosed, for example by WO-A-2008/009317, are seals in which one and the same attached sealing washer, for example consisting of a PTFE composition, forms the external or internal static seal and the internal or external dynamic sealing lip, making production easier and reducing costs in particular.
These types of seals are generally mounted in a wedged manner in a corresponding reception opening, for example an aperture or a corresponding through-opening formed in an envelope or a casing for the passage of a moving part, for example an axle or a rotary shaft.
It is advantageous, under these conditions, to be able to guarantee a rigid and wedged mounting of the seal in the aperture or the analogous reception opening, without employing any additional securing or fixing means, and simultaneously to provide the conditions for optimum static sealing between the outer periphery of the seal with a circular structure and the aperture or the analogous reception opening receiving it.
Preferably, this mounting should be able to take place with force or under radial stress, ensuring static sealing (between the ring and the housing) by compression of the part of the sealing washer secured to the axial leg.
Finally, it is desired in many applications to maintain sealing between the seal and reception opening in the case of dimensional variations, for example due to changes in temperature.
An object of the application is therefore to provide a seal of the type mentioned in the introduction of the present invention that makes it possible to satisfy the requirements expressed above.